This invention relates to underwater sound producing means and more particularly to means for producing low frequency sound waves.
Many years of research have been spent in a search for more efficient sonar equipment. Basically sonar equipment has been limited to magnetostrictive and piezoelectric types. These have been used as single transducer elements and in arrays for transmitting and receiving underwater sound waves. Better and more sophisticated equipment, including computers and accurate timing devices, has aided in improving underwater devices for detecting underwater signals. These detection devices encounter many problems in detection of low frequencies. Low frequencies imply longer wavelengths and longer wavelengths require larger transducers to produce them. Piezoelectric devices are brittle and their physical properties preclude their use because of the extended motion required to produce low frequencies.
Magnetostrictive materials operate low efficiency requiring large bulky devices which are impractical.